php - 我的加入声明有什么问题？它在 PHP 中返回 BOOLEAN

Question

为了让我的问题尽可能清楚(我之前曾提示太含糊)，下面是我在一个项目中使用的两个表的结构和数据。 表1包含足球比赛列表，表2包含将在表1中记录的英国足球队。

我刚刚从从图书馆借来的书中学习 SQL。我已按照有关加入表数据的说明进行操作。在这里，我只是尝试将数据回显到页面上，以确保在围绕该数据设置页面样式之前我的查询是正确的。

    <?php
        //Set DB Variables
        $dbc = mysql_connect(host, username, password);
        $db = mysql_select_db(database);
        $results= mysql_query("SELECT 'tbl_games.game_ID', 'tbl_games.game_date', 'tbl_teams.team_name' FROM tbl_teams, tbl_games
            WHERE 'tbl_games.team1_ID' = 'tbl_teams.team_ID' AND 'tbl_games.team2_ID' = 'tbl_teams.team_ID' AND 'tbl_games.team1_score' IS NULL AND 'tbl_games.team2_score' IS NULL");
        while ($row = mysql_fetch_array($results)) {
            foreach ($row as $columnName => $results) {
                echo 'Column name: '.$columnName.' Column data: '.$columnData.'<br/>';
            }
        }
    ?>

当我运行代码时，页面上没有打印任何错误，它只是不打印任何内容。但是已经(或者至少应该)出现了一些结果。我在这里做错了什么？

--
-- Table structure for table `tbl_games`
--

DROP TABLE IF EXISTS `tbl_games`;
CREATE TABLE IF NOT EXISTS `tbl_games` (
  `game_ID` int(6) NOT NULL AUTO_INCREMENT,
  `team1_ID` int(4) NOT NULL,
  `team2_ID` int(4) NOT NULL,
  `team1_score` int(2) DEFAULT NULL,
  `team2_score` int(2) DEFAULT NULL,
  `game_date` date NOT NULL,
  PRIMARY KEY (`game_ID`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=121 ;

--
-- Dumping data for table `tbl_games`
--

INSERT INTO `tbl_games` (`game_ID`, `team1_ID`, `team2_ID`, `team1_score`, `team2_score`, `game_date`) VALUES
(1, 42, 34, NULL, NULL, '2013-08-23'),
(2, 159, 45, NULL, NULL, '2013-08-23'),
(3, 5, 122, NULL, NULL, '2013-08-23'),
(4, 67, 12, NULL, NULL, '2013-08-24'),
(5, 60, 155, NULL, NULL, '2013-08-24'),
(6, 78, 105, NULL, NULL, '2013-08-24'),
(7, 101, 156, NULL, NULL, '2013-08-24'),
(8, 134, 144, NULL, NULL, '2013-08-24'),
(9, 142, 47, NULL, NULL, '2013-08-24'),
(10, 13, 88, NULL, NULL, '2013-08-24'),
(11, 21, 120, NULL, NULL, '2013-08-24'),
(12, 19, 16, NULL, NULL, '2013-08-24'),
(13, 20, 123, NULL, NULL, '2013-08-24'),
(14, 26, 29, NULL, NULL, '2013-08-24'),
(15, 36, 51, NULL, NULL, '2013-08-24'),
(16, 77, 21, NULL, NULL, '2013-08-24'),
(17, 81, 84, NULL, NULL, '2013-08-24'),
(18, 85, 18, NULL, NULL, '2013-08-24'),
(19, 132, 96, NULL, NULL, '2013-08-24'),
(20, 162, 50, NULL, NULL, '2013-08-24'),
(21, 22, 131, NULL, NULL, '2013-08-24'),
(22, 25, 152, NULL, NULL, '2013-08-24'),
(23, 86, 46, NULL, NULL, '2013-08-24'),
(24, 97, 27, NULL, NULL, '2013-08-24'),
(25, 107, 140, NULL, NULL, '2013-08-24'),
(26, 109, 115, NULL, NULL, '2013-08-24'),
(27, 127, 133, NULL, NULL, '2013-08-24'),
(28, 146, 69, NULL, NULL, '2013-08-24'),
(29, 150, 112, NULL, NULL, '2013-08-24'),
(30, 2, 38, NULL, NULL, '2013-08-24');

-- --------------------------------------------------------

--
-- Table structure for table `tbl_teams`
--

DROP TABLE IF EXISTS `tbl_teams`;
CREATE TABLE IF NOT EXISTS `tbl_teams` (
  `team_ID` int(4) NOT NULL AUTO_INCREMENT,
  `team_name` varchar(50) COLLATE latin1_general_ci NOT NULL,
  PRIMARY KEY (`team_ID`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 COLLATE=latin1_general_ci AUTO_INCREMENT=164 ;

--
-- Dumping data for table `tbl_teams`
--

INSERT INTO `tbl_teams` (`team_ID`, `team_name`) VALUES
(1, 'Aberdeen'),
(2, 'Accrington Stanley'),
(3, 'AFC Bournemouth'),
(4, 'AFC Wimbledon'),
(5, 'Airdrieonians'),
(6, 'Albion Rovers'),
(7, 'Aldershot Town'),
(8, 'Alfreton Town'),
(9, 'Alloa Athletic'),
(10, 'Annan Athletic'),
(11, 'Arbroath'),
(12, 'Arsenal'),
(13, 'Aston Villa'),
(14, 'Ayr United'),
(15, 'Barnet'),
(16, 'Barnsley'),
(17, 'Berwick Rangers'),
(18, 'Birmingham City'),
(19, 'Blackburn Rovers'),
(20, 'Blackpool'),
(21, 'Bolton Wanderers'),
(22, 'Bradford City'),
(23, 'Braintree Town'),
(24, 'Brechin City'),
(25, 'Brentford'),
(26, 'Brighton & Hove Albion'),
(27, 'Bristol City'),
(28, 'Bristol Rovers'),
(29, 'Burnley'),
(30, 'Burton Albion'),
(31, 'Bury'),
(32, 'Cambridge United'),
(33, 'Cardiff City'),
(34, 'Carlisle United'),
(35, 'Celtic'),
(36, 'Charlton Athletic'),
(37, 'Chelsea'),
(38, 'Cheltenham Town'),
(39, 'Chester'),
(40, 'Chesterfield'),
(41, 'Clyde'),
(42, 'Colchester United'),
(43, 'Coventry City'),
(44, 'Cowdenbeath'),
(45, 'Crawley Town'),
(46, 'Crewe Alexandra'),
(47, 'Crystal Palace'),
(48, 'Dagenham & Redbridge'),
(49, 'Dartford'),
(50, 'Derby County'),
(51, 'Doncaster Rovers'),
(52, 'Dumbarton'),
(53, 'Dundee'),
(54, 'Dundee United'),
(55, 'Dunfermline'),
(56, 'East Fife'),
(57, 'East Stirlingshire'),
(58, 'Elgin City'),
(59, 'England'),
(60, 'Everton'),
(61, 'Exeter City'),
(62, 'Falkirk'),
(63, 'FC Halifax Town'),
(64, 'Fleetwood Town'),
(65, 'Forest Green Rovers'),
(66, 'Forfar Athletic'),
(67, 'Fulham'),
(68, 'Gateshead'),
(69, 'Gillingham'),
(70, 'Greenock Morton'),
(71, 'Grimsby Town'),
(72, 'Hamilton Academical'),
(73, 'Hartlepool United'),
(74, 'Heart of Midlothian'),
(75, 'Hereford United'),
(76, 'Hibernian'),
(77, 'Huddersfield Town'),
(78, 'Hull City'),
(79, 'Hyde'),
(80, 'Inverness Caledonian Thistle'),
(81, 'Ipswich Town'),
(82, 'Kidderminster Harriers'),
(83, 'Kilmarnock'),
(84, 'Leeds United'),
(85, 'Leicester City'),
(86, 'Leyton Orient'),
(87, 'Lincoln City'),
(88, 'Liverpool'),
(89, 'Livingston'),
(90, 'Luton Town'),
(91, 'Macclesfield Town'),
(92, 'Manchester City'),
(93, 'Manchester United'),
(94, 'Mansfield Town'),
(95, 'Middlesbrough'),
(96, 'Millwall'),
(97, 'Milton Keynes Dons'),
(98, 'Montrose'),
(99, 'Morecambe'),
(100, 'Motherwell'),
(101, 'Newcastle United'),
(102, 'Newport County'),
(103, 'Northampton Town'),
(104, 'Northern Ireland'),
(105, 'Norwich City'),
(106, 'Nottingham Forest'),
(107, 'Notts County'),
(108, 'Nuneaton Town'),
(109, 'Oldham Athletic'),
(110, 'Oxford United'),
(111, 'Partick Thistle'),
(112, 'Peterborough United'),
(113, 'Peterhead'),
(114, 'Plymouth Argyle'),
(115, 'Port Vale'),
(116, 'Portsmouth'),
(117, 'Preston North End'),
(118, 'Queen of the South'),
(119, 'Queen''s Park'),
(120, 'Queens Park Rangers'),
(121, 'Raith Rovers'),
(122, 'Rangers'),
(123, 'Reading'),
(124, 'Republic of Ireland'),
(125, 'Rochdale'),
(126, 'Ross County'),
(127, 'Rotherham United'),
(128, 'Salisbury City'),
(129, 'Scotland'),
(130, 'Scunthorpe United'),
(131, 'Sheffield United'),
(132, 'Sheffield Wednesday'),
(133, 'Shrewsbury Town'),
(134, 'Southampton'),
(135, 'Southend United'),
(136, 'Southport'),
(137, 'St Johnstone'),
(138, 'St Mirren'),
(139, 'Stenhousemuir'),
(140, 'Stevenage'),
(141, 'Stirling Albion'),
(142, 'Stoke City'),
(143, 'Stranraer'),
(144, 'Sunderland'),
(145, 'Swansea City'),
(146, 'Swindon Town'),
(147, 'Tamworth'),
(148, 'Torquay United'),
(149, 'Tottenham Hotspur'),
(150, 'Tranmere Rovers'),
(151, 'Wales'),
(152, 'Walsall'),
(153, 'Watford'),
(154, 'Welling United'),
(155, 'West Bromwich Albion'),
(156, 'West Ham United'),
(157, 'Wigan Athletic'),
(158, 'Woking'),
(159, 'Wolverhampton Wanderers'),
(160, 'Wrexham'),
(161, 'Wycombe Wanderers'),
(162, 'Yeovil Town'),
(163, 'York City');

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

Answer 1

您的查询(在 PHP 代码中)中的那些单引号 ' 应该是反引号 `，就像它们在您创建表的语句中一样。

否则，您在 where 子句中比较不匹配的文字字符串。

另外，除非绝对必要，否则我不太喜欢使用反引号。在我看来，它通常会降低 SQL 语句的可读性。它有它的位置，当然有些人可能更喜欢一致性而不是可读性，但我不是其中之一:-)

但是，即使您解决了这个问题，您仍然会遇到以下问题:

WHERE tbl_games.team1_ID = tbl_teams.team_ID
  AND tbl_games.team2_ID = tbl_teams.team_ID

因为你似乎在要求所有那些球队与自己比赛的比赛，这是我在很多体育比赛中都没有见过的。

您需要重新考虑您的要求。例如，如果您只是想要一支球队进行的所有比赛(作为球队 1 或 2)，您可以使用 OR 而不是 AND(并使用括号来确保 AND/OR 的正确混合)。